The invention set forth in this specification relates to new and improved dispensing closures. More specifically, it relates to the construction of such closures so as to minimize the chances of such closures leaking.
At the present time the term "dispensing closures" is commonly used to designate closures which are constructed so as to include a cap or a part of a container in effect serving as a cap, and a spout movably mounted upon such a cap or related part so as to be capable of being moved between open and closed positions. In such a closed position a portion of the spout normally referred to as the base of the spout fits with respect to the opening so that the opening is sealed off against leakage. In such an open position a passage through the spout is aligned with the opening.
Such dispensing closures are commonly manufactured in significant quantities using parts formed of various polyolefin polymers such as various injection moldable grades of polyethylene, polypropylene or out of various polymers that are closely related to these specific polymers. Dispensing closures manufactured out of such materials are normally constructed so as to utilize a sealing element or sealing means located around the cap or cap-like part of such a closure in order to prevent or minimize leakage between the spout and such a cap or cap-like part. Since virtually the advent of dispensing closures formed of materials as noted such leakage has been a significant problem to the industry. It would be possible to encumber this specification with a prolonged, detailed discussion as to various different specific structures which have been developed at various times and which have been effective to an increasingly greater degree in combatting leakage between a cap and a spout in a dispensing closure.
This problem of leakage in dispensing closures using parts manufactured from polyolefins and related materials is considered to be comparatively complex and to have many different facets. It is now considered to be well established that different types of fluids have different propensities towards leakage in such closures. Such leakage is most commonly minimized by holding the spout in a dispensing closure against a somewhat resilient, flexible sealing ring located around the opening through the cap of such a closure with sufficient force so that such force in combination with the inherent flexibility of the sealing ring will form an effective seal against leakage of most fluids.
The fact that seals as described in a general manner in the preceding discussion are reasonably effective in dispensing closures is amply evidenced by the fact that millions of such closures are manufactured and utilized every month on a wide variety of diverse products. However, it is considered that there still exists a need for improvement in the construction of dispensing closures so as to further reduce or minimize the possibility of such closures leaking. It is considered that this need is especially important in connection with the use of dispensing closures with various fluids which for one reason or another at times leak past the sealing structures as they are employed in presently existing dispensing closures.